The communications industry is rapidly changing to adjust to emerging technologies and ever increasing customer demand. This customer demand for new applications and increased performance of existing applications is driving communications network and system providers to employ networks and systems having greater speed and capacity (e.g., greater bandwidth). In trying to achieve these goals, a common approach taken by many communications providers is to use packet switching technology. Increasingly, communications service providers are building their communications infrastructure based on packet technology, and in particular, ATM technology, and providing voice over ATM communications services.
Providers and consumers of these communications services desire to have reliable voice over ATM services which efficiently and securely use the bandwidth and other resources of the access and core portions of the ATM networks. It is critical to a services provider that their network not be susceptible to theft of services or denial of service of other disruptions to its customers, which may transpire especially if customer premises equipment is allowed to setup switched virtual circuits (SVCs) using conventional techniques in the core ATM network.
Communications networks used to provide voice of ATM services typically have plenty of bandwidth available in the ATM core network, while bandwidth may be scarce in the access network. One approach in addressing the bandwidth resource issue in the access network is to use ATM Adaptive Layer 2 (AAL2) where multiple voice channels are multiplexed over an access link. AAL2 is especially useful for general purpose voice trunking, but its use in the core is not scaleable to large networks because it incurs the call processing and provisioning overhead of a two-tier network architecture (i.e., an AAL2 overlay network on top of an ATM network). Also, because AAL2 performs a function similar to a time division multiplexing hierarchical trunking architecture, it fails to fully exploit the flexible routing capabilities of Private Network-Network Interface (PNNI) ATM networks. PNNI is a trunking, routing, and signaling protocol which applies to a network of ATM switches, and in some cases, ATM-connected edge devices.
A network which used per-call SVCs in the access network (e.g., without AAL2 multiplexing) typically results in inefficient bandwidth usage, especially on leased lines with high recurring costs. This SVC approach also provides some additional security concerns.
Needed are new approaches and systems for seamlessly providing ATM calls over the access and core network portions of an ATM network and that marry the best aspects of AAL2 and ATM SVC connections.